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Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11
Times Cited Count：3 Percentile：90.77Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12
Times Cited Count：6 Percentile：92.96Nakamoto, Tatsushi*; Sugano, Michinaka*; Xu, Q.*; Kawamata, Hiroshi*; Enomoto, Shun*; Higashi, Norio*; Idesaki, Akira; Iio, Masami*; Ikemoto, Yukio*; Iwasaki, Ruri*; et al.
IEEE Transactions on Applied Superconductivity, 25(3), p.4000505_1 - 4000505_5, 2015/06
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)Recently, development of superconducting magnet system with high radiation resistance has been demanded for application in accelerator facilities such as CERN LHC. In order to realize superconducting magnet system with high radiation resistance, it is necessary to develop electrical insulator with high radiation resistance because the electrical insulator is made of organic materials whose radiation resistance is inferior to that of inorganic materials. We developed a glass fiber reinforced plastic with bismaleimide-triazine resin. The developed material showed excellent radiation resistance; the material evolved gases of 5
10 
mol/g and maintained flexural strength of 640MPa (90% of initial value).
Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.
Journal of Nuclear Materials, 458, p.369 - 375, 2015/03
Times Cited Count：7 Percentile：60.95(Materials Science, Multidisciplinary)To validate Monte Carlo codes for the prediction of radiation damage in metals irradiated by 
100 MeV protons, defect-induced electrical resistivity changes of copper related to the displacement cross-section were measured with 125 MeV proton irradiation at 12 K. The cryogenic irradiation system was developed with a Gifford-McMahon cryocooler to cool the sample via an oxygen-free high-conductivity copper plate by conduction cooling. The sample was a copper wire with a 250
m diameter and 99.999% purity sandwiched between two aluminum nitride ceramic sheets. The resistivity increase did not change during annealing after irradiation below 15 K. The experimental displacement cross-section for 125 MeV irradiation shows similar results to the experimental data for 1.1 and 1.94 GeV. Comparison with the calculated results indicated that the defect production efficiency in Monte Carlo codes gives a good quantitative description of the displacement cross-section in the energy region 100 MeV.
Ito, Takayoshi; Harjo, S.; Osamura, Kozo*; Hemmi, Tsutomu; Awaji, Satoshi*; Machiya, Shutaro*; Oguro, Hidetoshi*; Nishijima, Gen*; Takahashi, Koki*; Matsui, Kunihiro; et al.
Materials Science Forum, 681, p.209 - 214, 2011/05
Times Cited Count：1 Percentile：58.22Nakamoto, Tatsushi*; Ohata, Hirokatsu*; Ogitsu, Toru*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 31, 2007/02
Radiation resistance of organic materials used in superconducting magnets for a 50 GeV - 750 kW proton beam line for the J-PARC neutrino experiment was studied with respect to mechanical properties. Specimens cooled at a liquid nitrogen temperature of 77 K were irradiated by 
rays. The flexural strength of glass-fiber reinforced plastics (GFRPs), the tear strength of polyimide films and the tensile strength of adhesive films were evaluated. It was verified that the organic materials used in the superconducting magnets have the sufficient radiation resistance, and the degradation of thier mechanical properties after the 10 years operation was estimated to be negligible.
Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 32, 2007/02
Radiation resistance of polymeric materials used in the superconducting magnets installed for the J-PARC neutrino beam line was studied with respect to gas evolution. The polymeric materials were irradiated by rays at 77K. It was found that hydrogen gas evolved mainly from the polymeric materials, and the amount of hydrogen from whole superconducting magnet system per 1 year was estimated to be 0.37mol. This amount of hydrogen is low enough to be removed by a hydrogen absorbing apparatus. Therefore, the influence of hydrogen evolved from the magnet system on the operation of the helium purifying system can be negligible.
Makida, Yasuhiro*; Ohata, Hirokatsu*; Okamura, Takahiro*; Ogitsu, Toru*; Nakamoto, Tatsushi*; Kimura, Nobuhiro*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 34, 2007/02
A string of superconducting magnets is to be set at an arc section of the J-PARC neutrino beam line. To keep the magnets at superconducting condition, a helium cryogenic facility is to be constructed. Parts of cryogenic devices are located beside the magnets, so thier resistance to radiation with predicted dose of 1 MGy in maximum must be assured. A cryogenic control valve is one of the active devices used in the radio-active area, and its radio-proof characteristics is improved by (1) exchaging intolerant materials by proof ones, (2) moving the feed back control circuit unit including electronics from the valve body to a low radio-active area. Two prototype valves, a tuning valve and a Gauzky relief valve, have been prepared and have been tested by using the Cobalt 60 irradiation facility in JAEA. Actual operations of the both prototypes have been checked at the irradiation test bench, and they were successfully operated after irradiation of 1 MGy.
Idesaki, Akira; Morishita, Norio; Ito, Hisayoshi; Kamiya, Tomihiro; Nakamoto, Tatsushi*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Ogitsu, Toru*; Ohata, Hirokatsu*; Yamamoto, Akira*
AIP Conference Proceedings 824, p.330 - 334, 2006/03
Polyimide films and glass fiber reinforced plastics (GFRPs) are used as insulating or structural materials for superconducting magnets in a neutrino beam line of the Japan Proton Accelerator Research Complex (J-PARC). It is indispensable to evaluate radiation resistance of these materials, because they are required to keep their electrical and mechanical properties in a high radiation field of 30 kGy/year at low temperature of 4 K. In this work, the gas evolution resulting from chemical reactions induced in the polyimide films and GFRPs by ray irradiation at 77 K was investigated. It was found that the main component of the evolved gas is hydrogen. The amount of hydrogen evolved from the superconducting magnet system used in the neutrino beam line was estimated to be 0.37 mol/year (0.01 L/year as the volume of liquid hydrogen). It indicates that the hydrogen evolved from the organic materials does not influence on the operation of the helium purifying system.
Nakamoto, Tatsushi*; Idesaki, Akira; Morishita, Norio; Ito, Hisayoshi; Kamiya, Tomihiro; Kimura, Nobuhiro*; Makida, Yasuhiro*; Ogitsu, Toru*; Ohata, Hirokatsu*; Yamamoto, Akira*
AIP Conference Proceedings 824, p.225 - 232, 2006/03
Radiation resistance with respect to mechanical properties of organic materials used in the superconducting magnets for the 50 GeV - 750 kW proton beam line for the J-PARC neutrino experiment was studied. Specimens cooled at liquid nitrogen temperature of 77 K were irradiated by gamma rays beyond 10 MGy. The flexural strength of glass-fiber reinforced plastics (GFRPs), the tear strength of polyimide films and the tensile lap-shear strength of adhesive films were evaluated. It was verified that the organic materials used in the superconducting magnet have a sufficient radiation resistance, and the degradation of their mechanical properties after 10 years operation was estimated to be negligible.
-ray irradiation effects on polymeric materials in superconducting magnets for the J-PARC neutrino experiment, 2; Gas evolutionIdesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*
no journal, ,
Irradiation effect on polymeric materials used in the superconducting magnets for the J-PARC neutrino beam line was studied with respect to gas evolution. The polymeric materials were irradiated by -ray at 77K. It was found that hydrogen gas evolves mainly from the polymeric materials, and that the amount of hydrogen from whole superconducting magnet system per 1 year is 0.37mol. Furthermore, it was found that the amount of gas evolution increases with increasing in the storage time at room temperature after the irradiation at 77K.
-ray irradiation effects on polymeric materials in superconducting magnets for the J-PARC neutrino experiment, 1; Mechanical propertiesIdesaki, Akira; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi
no journal, ,
Radiation resistance of polymeric materials used in superconducting magnets for a 50 GeV-750 kW proton beam line for the J-PARC neutrino experiment was studied with respect to mechanical properties. Specimens were irradiated by rays with the maximum dose beyond 10 MGy. It was verified that the polymeric materials have the sufficient radiation resistance, and the degradation of their mechanical properties after the 10 years operation was estimated to be negligible.
Makida, Yasuhiro*; Iida, Masahisa*; Ohata, Hirokatsu*; Okamura, Takahiro*; Ogitsu, Toru*; Kimura, Nobuhiro*; Tanaka, Kenichi*; Nakamoto, Tatsushi*; Yamamoto, Akira*; Idesaki, Akira; et al.
no journal, ,
A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. Since the magnet system will be exposed to high radiation field, the radiation resistance of a cryostat is very important. We have developed radio-proof control valve and relief valve by selection of some parts and separation of the positioner. In this work, the developed valves were worked under the ray irradiation, and it was found that the valves show the radiation resistance above 1MGy.
-ray irradiation effects on organic materials at 77 KNakamoto, Tatsushi*; Ohata, Hirokatsu*; Ogitsu, Toru*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Idesaki, Akira; Ito, Hisayoshi; Morishita, Norio
no journal, ,
A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. GFRPs whose matrices are phenol resin and epoxy resin, and polyimides are used as structural materials and electrical insulation. Radiation resistance of these polymeric materials is very important, because they are exposed to high radiation field. In this work, specimens were irradiated by rays with the maximum dose beyond 10MGy at liquid nitrogen temperature (77K), and the properties of gas evolution and mechanical strength were investigated. It was verified experimentally that the polymeric materials have sufficient radiation resistance for the using in the J-PARC neutrino beam line.
-ray irradiation effects on polymeric materials in superconducting magnets; Gas evolutionIdesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*
no journal, ,
Irradiation effect on polymeric materials used in the superconducting magnets for the J-PARC neutrino beam line was studied with respect to gas evolution. The polymeric materials were irradiated by -ray at 77K. It was found that hydrogen gas evolves mainly from the polymeric materials, and that the amount of hydrogen from whole superconducting magnet system per 1 year is 0.37 mol.
-ray irradiation effects on polymeric materials in superconducting magnets; Mechanical propertiesNakamoto, Tatsushi*; Ohata, Hirokatsu*; Ogitsu, Toru*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi
no journal, ,
A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. GFRPs whose matrices are phenol resin and epoxy resin, and polyimides are used as structural materials and electrical insulation. Radiation resistance of these polymeric materials is very important, because they are exposed to high radiation field. In this work, specimens were irradiated by rays with the maximum dose beyond 10 MGy at liquid nitrogen temperature (77K), and the mechanical properties were investigated. It was verified experimentally that the polymeric materials have sufficient radiation resistance for the using in the J-PARC neutrino beam line.
Makida, Yasuhiro*; Ohata, Hirokatsu*; Okamura, Takahiro*; Ogitsu, Toru*; Nakamoto, Tatsushi*; Kimura, Nobuhiro*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio
no journal, ,
A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. Since the magnet system will be exposed to high radiation field, the radiation resistance of a cryostat is very important. We have developed radio-proof control valve and relief valve by selection of some parts and separation of the positioner. In this work, the developed valves were worked under the ray irradiation, and it was found that the valves show the radiation resistance above 1 MGy.
Iwamoto, Yosuke; Yoshida, Makoto*; Nakamoto, Tatsushi*; Ogitsu, Toru*; Yoshiie, Toshimasa*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Mori, Yoshiharu*
no journal, ,
We measured the electrical resistivity under irradiation of 125 MeV proton in copper sample (0.2 um thickness) at cryogenic temperature at the FFAG accelerator facility in Kyoto university. Resistivity was measured by the four-terminal method. As a result, we measured the resistivity of copper at 7.3 K within 20 micro-ohm and temperature of sample. We measured the electrical resistivity under irradiation of 125 MeV proton in copper sample (0.2 um thickness) at cryogenic temperature at the FFAG accelerator facility in Kyoto university. Resistivity was measured by the four-terminal method. As a result, we measured the resistivity of copper at 7.3 K within 20 micro-ohm and temperature of sample.
Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.
no journal, ,
To validate the radiation damage calculation in the PHITS code for proton irradiation over 100 MeV, we have developed the device for electrical resistance measurement under cryogenic condition. A copper wire with 99.999% purity in a diameter of 250-m was set with a serpentine-shaped line on the AlN sheet which has high thermal conductivity and electric insulation. The sample was annealed for 1 h at 1,000
C before irradiation. After annealing, the sample was cooled with an oxygen-free high-conductivity copper plate by conduction cooling. The electrical resistivity changes in the sample were measured using the four-probe technique. As a result, the residual resistivity ratio of the sample was about 1,800 between room temperature and 11 K. After 125 MeV proton irradiation with 1.4510
(proton/cm
) at 11 K, the total resistance increase was 1.53 
, while the resistivity of copper before irradiation was 29.41 .
Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.
no journal, ,
To validate Monte Carlo code PHITS for the prediction of radiation damage in metals, the damage rate (defect-induced electrical resistivity changes / particle fluence) related to the displacement cross-section of copper were measured with 125 MeV proton irradiation under 12 K at the FFAG facility in the Kyoto University Research Reactor Institute. The sample was a copper wire with a 250-m diameter and 99.999% purity and was cooled by conduction cooling. After 125 MeV proton irradiation with 1.4510
protons/m at 12 K, the total resistivity increase was 4.9410
m (resistance increase: 1.53), while the resistivity of copper before irradiation was 9.49 10
m (resistance: 29.41). Comparison with other experimental results indicated that the damage rate by 125 MeV protons is almost same with those by 1.1 GeV protons and is higher than the damage rate by 14 MeV neutrons by a factor of 1.4. For the comparison with the PHITS results, the experimental data is smaller than the calculated result without the defect production efficiency by a factor of about 2.5 and that with the defect production efficiency by a factor of about 1.4, respectively. It indicates that the defect production efficiency in PHITS gives a good quantitative description of the displacement cross-section.
